The task of determining shape boundaries in images arises in various fields including cartography, robotics and medical diagnostics, for example. Such tasks may be met by direct visual inspection, but, e.g. for processing large numbers of images, automated techniques are desired.
One such technique for shape determination involves iterative adjustment of a shape model such as a flexible line, called a "snake", with the goal of optimizing an objective function. For example, the line may be adjusted so that a parametric combination of its smoothness and the cumulative strength and proximity of nearby image edges is maximized. Analogous techniques can be used for higher-dimensional shapes, e.g. using a flexible surface for modeling the boundary of a spatial volume.